RotateRight is an equivalent to Matlab fftshift.
img=Import["ExampleData/lena.tif"];
d=ImageData[img,Interleaving->False][[2]];
{nRow,nCol}=ImageDimensions[img];
fw=Fourier[d,FourierParameters->{1,1}];
fw = RotateRight[fw,Floor[({nCol,nRow}-1)/2]]; (*center,i.e.fftshift like*)
(*adjust for better viewing as needed*)
fudgeFactor=100;
abs=fudgeFactor*Log[1+Abs@fw];
Labeled[Image[abs/Max[abs],ImageSize->300],Style["Magnitude spectrum",18]]
arg=Arg@fw;
Labeled[Image[arg/Max[arg],ImageSize->300],Style["Phase spectrum",18]]
If you only need a magnitude spectrum, then ImagePeriodogram has an Alignment option that determines the location of the zero frequency term.
